Temperature regulating block with receivers

ABSTRACT

A temperature regulating block for lab thermostatting systems has a receiving side with two kinds of seats in the form of differently shaped recesses to implement large-area contact-making seating of filled lower zones of two differently shaped kinds of receptacles filled with sample liquid. At least one temperature regulator is in contact with the block. The two kinds of seats are arranged in a regular, two-dimensional grid such that a seat of one kind in each case is located between four seats of the other kind.

FIELD OF THE INVENTION

The present invention relates to a temperature regulating block for labthermostatting systems having a receiving side with recessed seats toimplement large-area contact seating of filled, lower zones ofreceptacles filled with sample liquids and having at least onetemperature regulator with which it is in contact.

BACKGROUND OF THE INVENTION

A temperature regulating block of this general type is known from U.S.Pat. No. 5,525,300 wherein the seats are identical recesses receivingone kind of receptacles and are in rows and columns in the temperatureregulating block.

This has the drawback, first, that only one kind of receptacle can beused. If, as occurs in the lab, different kinds of receptacles must beused, the temperature regulating block must then be replaced becauseinadequate thermal contact would result if the containers were less thanoptimally matched to the recesses. Moreover, the recesses forming theseats are significantly separated from one another in this known design.Accordingly, the temperature regulating block is quite heavy and itsheat capacity is high. The temperature of such a temperature regulatingblock can only be changed slowly. Another drawback is the excellentthermal conductivity of the block, entailing high heat flux whentemperature gradients are produced and demanding large energies forheating and cooling. If the temperature regulating block is used at aregulated temperature differential by multiple temperature regulators toproduce a temperature gradient, then the heat flux between thetemperature regulators also will exist between the recesses, and thetemperature distribution may be non-uniform.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a temperatureregulating block of the type mentioned above which assures rapidly astate of optimal temperature distribution for different vessels.

The invention provides two kinds of recesses to seat differentreceptacles. Accordingly, the temperature regulating block acceptsreceptacles of one kind as well as of the other, optionally evensimultaneously. As a result, the thermostatting systems for lab work canbe operated in a significantly more flexible manner. Because of thelarge number of mutually nesting recesses, the temperature regulatingblock is made substantially thinner, and its overall weight isrelatively very modest. Thereby its heat capacity is reduced and thetemperature regulating block can be made to more rapidly assume thedesired temperatures. Illustratively, samples received in a temperatureregulating block can be rapidly and consecutively made to assumedifferent temperature levels. By thinning the material of thetemperature regulating block, its thermal conductivity is reduced, i.e.,its thermal impedance is raised. If the temperature regulating block isoperated with several temperature regulators in turn operated indifferent manners to implement a temperature gradient, then a slightheat flux suffices because of the high thermal impedance, andconsequently the energy consumption for heating and cooling can besubstantially reduced. By situating the recesses at the receptaclereceiving side, the thick segments of the temperature regulating blockare reduced, especially at the seating side. When differentially heatingthe temperature regulating block for achieving a temperature gradient,there is a lesser heat flux in that zone than in the lower segment ofthe temperature regulating block. As a result, uniformity of temperaturedistribution is improved.

By arranging the seats of one shape in a predetermined gridconfiguration in the temperature regulating block, the block is usablewith such receptacles mounted in a predetermined grid and illustrativelyconnected in a plate configuration.

By providing a hole between each two seats of each kind, the uppersegment near the receiving side of the temperature regulating block isthinned further.

It is advantageous to form the block so that the part underneath therecesses and any holes is a continuous plate. The heat flux is therebymade to pass through a plate segment of very good thermal conductivitywhich evens the temperatures in the temperature regulating block. Thetemperature then resulting in the temperature regulating block isessentially determined by the temperature distribution in the platewhereas the part of the temperature regulating block fitted with therecesses laterally taps the plate temperatures without adverselyaffecting them. A temperature regulating block including a continuousplate segment underneath the part thinned by recesses also isadvantageous in implementing a uniform temperature through the entiretemperature regulating block when the block is operated without atemperature gradient. The lamellar lower part of the temperatureregulating block furthermore assures good contact withtemperature-regulating means present therein.

Increased thermal-impedance zones illustratively may be used to controlthe heat flux in the temperature regulating block, for instance toreduce this flux between adjacent temperature regulators when such areused to generate a temperature gradient. In this manner regulationfluctuations in the temperature regulators may be decreased. These zonesalso may be used to locally control the temperature gradients, forinstance, to control the temperature curve through the full temperatureregulating block, illustratively to linearize it. The invention, whereinthe zones are grooves, is advantageous over the design of the initiallycited art of boreholes. Grooves are more easily made. In particular theybegin at the contacting side and thus they thin the continuous plate ofthe temperature regulating block, contributing predominantly to heatconduction. The grooves in particular may meander between the recessesand holes so as to be a safe distance from said recesses and holes evenwhen the grooves are deep.

Providing several temperature regulators at a contacting side of theblock opposite the receiving side allows setting samples at differenttemperatures in one temperature regulating block. While the initiallycited design already allows doing so, it implements this feature bytemperature regulators acting on the ends of the temperature regulatingblock. The invention, on the other hand, offers the advantage that bylarge-surface contact with the temperature regulating block, theselected temperature profile can be very rapidly achieved over theblock's full length and that this block is thermally better controlledagainst ambient effects. Moreover, the temperature regulating block canbe operated at constant temperature in an alternate mode without resortto auxiliary apparatus, whereas the known design requires an additionaltemperature regulator resting against the contacting side. For thatpurpose, increased thermal-impedance zones are advantageously providedparallel to the activity boundaries and may directly adjoin them torestrict fluctuations in temperature regulation between the temperatureregulators, or they may be mounted above the temperature regulators tocontrol the temperature profile, for instance to linearize it. Thesezones may be in the form of grooves reducing the block's cross-sectionalarea. Furthermore, the contacting side may be fitted with temperatureregulators split in the longitudinal and transverse directions allowingone to set a temperature profile in either direction, for instance alsoalternatingly across the temperature regulating block or even in bothdirections.

It is possible to provide several temperature regulating blocksdisplaceable relative to a support which supports the receptacles andwhich can alternatingly move its seats flush with the receptacles. Thereceptacles in this arrangement, just as in the known design initiallydiscussed, are consecutively engaged by temperature regulating blockskept at different temperatures and either presenting a temperaturegradient or a constant temperature over their surfaces. For the purposeof lateral displacement, the temperature regulating blocks may bemounted in a laterally displaceable carriage. For the same purpose theyalso may be mounted in a rotor, for instance, rotating like a lazy susanin a plane parallel to the support. Preferably they are rotated by arotor about an axis parallel to the support to allow especially goodcompactness. The blocks may be displaced relative to the rotor toachieve spacing or preferably the rotor is displaced as a whole for thisspacing motion.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustratively and schematically shownin the accompanying drawings wherein:

FIG. 1 is a side elevation in section of a thermostatting system for labwork in accordance with the invention fitted with a first embodiment ofan alternating block drive;

FIG. 2 is a side elevation in section of a lab thermostatting system inaccordance with the invention with a second embodiment of an alternatingblock drive;

FIG. 3 is a side elevation in partial section of a first embodiment of atemperature regulating block for producing a temperature gradient;

FIG. 3a is a graph of a temperature gradient produced in the block shownin FIG. 3;

FIG. 4 is a side elevation of a second embodiment of a temperatureregulating block to produce a temperature gradient;

FIG. 4a is a graph of a temperature gradient in the block of FIG. 4;

FIG. 5 is a plan view of a temperature regulating block at thecontacting side with four quadrant-mounted temperature regulators;

FIG. 6 is a top plan view of a temperature regulating blockcorresponding to that of FIG. 4 and with a detailed view of the seats;and

FIG. 7 is a section along line 7—7 of FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a lab thermostatting system, especially appropriate for thePCR (poly chain reaction) process. In such a process, sample liquids,for instance reaction mixtures, must be consecutively raised todifferent temperatures.

Sample liquids are provided in receptacles 1 which, in the shownillustrative embodiments, are commercial reaction vials made ofthin-walled plastic. Each vial comprises a cylindrical zone which, asshown in FIG. 1, tapers conically at its lower end region which containsthe sample liquid. The upper edge is fitted with a collar 2 and with anelastically deformable cap 3 which seals the receptacle.

The lab thermostatting system shown comprises an enclosing housing 4with a support 5 at its top side in the form of a plate perforated byholes 6 which keep receptacles 1 in position and secure them at theircollars 2 against dropping.

A heat regulating block 7 is mounted underneath support 5 and comprisesseats 11 at its receiving side 10 which are in the form of pockets orrecesses, the shapes of these seats corresponding to that of the lowerends of receptacles 1. The arrangement of seats 11 in the surface ofreceiving side 10 of block 7 corresponds to the configuration of holes 6in support 5, in which seats 11 are aligned with holes 6, all ofreceptacles 1 in support 5 engaging seats 11 and the lower ends of thereceptacles making good thermal surface contact with block 7.

In order to secure good thermal surface contact between receptacles 1and seats 11 of block 7, a cover plate 12 is mounted above support 5 andpresses against elastic caps 3 of receptacles 1. To assure reliabletemperature regulation of the sample liquids in receptacles 1 and toprevent condensation on receptacle caps 3, cover plate 12 is raised to asuitable temperature by a temperature regulator 13, for instance aPeltier element with leads 14, that rests against the cover plate.

On its contacting side 15 opposite receiving side 10, block 7 is incontact with a temperature regulator 16. This temperature regulatorillustratively may be a Peltier element powered through leads 17. APeltier element is especially well suited for such purposes because itcan serve to heat or cool, depending on need.

Block 7 can be set to the desired temperature by temperature regulator16. Preferably, a temperature sensor is provided in block 7 for thispurpose and at a suitable location which, by means of an electronicregulating device, controls the temperature regulator 16 so that thetemperature in block 7 is kept constant at an appropriate level.

If, as shown, block 7 provides surface contact between receptacles 1 andrecesses 11, then the sample liquids very quickly and highly accuratelyassume the temperature of block 7, that is, the desired temperature ofreaction.

In the illustrative embodiment shown, the lab thermostatting systemcomprises two further blocks 8 and 9 with recessed seats 11corresponding to the already discussed block 7. Temperature regulatingblocks 8 and 9 also have temperature regulators, block 9 having atemperature regulator 16 and block 8 having two juxtaposed temperatureregulators 19 and 20 which can be operated in parallel to be at the sametemperature or alternatively, as described further below, at differenttemperatures. Temperature regulator 16 underneath temperature regulatingblock 9 has a cooling body 18 which furthermore may also be present atthe other temperature regulators and which is advantageous if thetemperature regulator is a Peltier element that must dissipate or acceptheat on its surface away from the temperature regulating block.

The configuration of recesses 11 in all three blocks 7, 8 and 9 isidentical. Therefore, each of the blocks can be made selectively toengage receptacles 1 in support 5.

A block-exchanging drive is provided for that purpose The blocks 7, 8and 9 are rigidly interconnected by braces 21 in one plane to alaterally displaceable carriage which rests in a slide guide 23 so as tobe longitudinally displaceable in the direction of arrow 24 by a pushrod22. The lateral drive so constituted for the temperature regulatingblocks 7, 8 and 9 is adjustable in height as a whole by a spacing drive.

To implement spacing, slide guide 23 is mounted on a pushrod 26 which isheight-adjustably supported for movement in the direction of arrow 28 ina slide guide 27.

Starting with the position of the temperature regulating blocks shown inFIG. 1 wherein the center temperature regulating block 7 engagesreceptacles 1, block 7 can be disengaged from the receptacles by beinglowered by slide guide 27. Thereupon, by adjusting pushrod 22 of thelateral drive, one of the two other blocks can be moved to a flushposition underneath support 5 and, following upward displacement insideslide guide 27, can be made to engage receptacles 1.

In this manner receptacles 1 seated in support 5 can be movedalternatingly into thermal contact with temperature regulating blocks 7,8 or 9. These blocks may be kept regulated at different temperatures.Accordingly, receptacles 1 can be subjected in rapid sequence todifferent, highly accurate temperatures, a feature which is especiallydesirable in the PCR procedure.

Just as the holes 6 in the support 5, seats 11 in temperature regulatingblocks 7, 8 and 9 may be configured appropriately, for instance in rowsand columns. Once cover plate 12 has been removed, the receptacles maybe replaced. Illustratively, they may be replaced with support 5 to savetime, support 5 then necessarily being replaceable relative to housing4.

Instead of the shown three temperature regulating blocks 7, 8 and 9,another number may also be used in the shown linear carriageconfiguration, depending on the number of temperature steps.

Moreover the configuration of lateral drive and spacing drive may bedifferent. Illustratively, the blocks may be connected throughindividual spacing drives to one lateral drive.

The blocks can be exchanged underneath receptacles 1 manually orpreferably using motor drives illustratively controlled by computers andimplementing in a way not shown the displacement of pushrod 22 relativeto its slide guide 23 and that of pushrod 26 relative to its slide guide27. In this manner, a temperature-control cycle of desired sequence canbe run in accordance with a control program

Instead of the block drive shown in FIG. 1 wherein the lateral drive isdesigned as a slide carriage with slide guide 22, 23, the lateral driveillustratively may also be in the form of a lazy susan. In that case theshown blocks 7, 8 and 9 must be mounted in a plane parallel to thesupport 5 and pivotable about an axis of rotation perpendicular to saidplane.

FIG. 2 shows a further advantageous embodiment of the block exchangingdrive. Parts of the drive structure correspond to that of FIG. 1. Asmuch as possible, the same parts are denoted by the same references.

Support 5 holding receptacles 1 is at the top side of a slightlymodified housing 4′. Again it is covered by a cover plate 12 assuringpressure on, and temperature regulation of, the receptacles from above.FIG. 2 additionally shows detachable locking means 29 that also may beprovided in the embodiment of FIG. 1 and which secure the cover plate 12in the shown position.

In the embodiment of FIG. 2, the lab temperature regulating systemcomprises the three temperature regulating blocks 7, 8 and 9 of FIG. 1and additionally a temperature regulating block 9′ of correspondingdesign. These temperature regulating blocks, including the associatedtemperature regulators, correspond to the embodiment of FIG. 1.Temperature regulating block 7 in its shown position engages receptacles1 flush under support 5.

The lateral motion of the temperature regulating blocks is, however,essentially different in FIG. 2 from that shown in FIG. 1.

Blocks 7, 8, 9 and 9′ are affixed at 90° positions to a rotor 30 held ina head 33 of pushrod 26 so as to be rotatable about an axis 31 in thedirection of the arrow 32, pushrod 26 being longitudinally displaceableinside slide guide 27 in the direction of arrow 28.

To exchange the temperature regulating blocks underneath support 5,first pushrod 26 together with rotor 30 is moved down until thetemperature regulating block previously just engaged is disengaged fromreceptacles 1. Rotor 30 is then rotated through an angle equal to amultiple of 90° to move another temperature regulating block flush withand underneath support 5 and to bring it into contact with receptacles 1by raising pushrod 26. In this embodiment, motor drives, not shown, maybe provided which illustratively are driven in fully automated manner bya computer control.

Comparison of FIGS. 1 and 2 shows that the embodiment of FIG. 2,employing a rotating drive for the temperature regulating blocks, ismore compact.

FIG. 3 is a side view of temperature regulating block 8 of FIGS. 1 and 2and its two temperature regulators 19 and 20 also in side view. Seats11′ used as recesses to hold the receptacles in this embodiment aresomewhat smaller in size and larger in number. Seats 11′ may be arrayedin rows and columns at the receiving side 10. They serve to receive asubstantial number of receptacles which are to be temperature regulated.

Temperature regulators 19 and 20 resting against contacting side 15 ofblock 8 preferably are Peltier elements fitted with power leads (notshown) from FIG. 3 for power application. As a result, arbitrarytemperatures may be implemented in heating or cooling manner. However,temperature regulators 19 and 20 also may be heat exchangers crossed byliquid flows and fed, for instance, by hose systems.

Temperature regulators 19 and 20 may be set at the same or at differenttemperatures. Temperature sensors in the block, not shown, above thetemperature regulators may be connected to a control system controllingthe heat input or dissipation implemented by the temperature regulators.

In the embodiment of FIG. 3, temperature regulators 19 and 20 each restagainst approximately half of contacting side 15. Good thermal contactcan be secured by bonding, screwing or other affixation means.

When temperature regulators 19 and 20 are set at different temperatures,in the case shown with temperature regulator 20 being at the highertemperature, there will ensue a longitudinal temperature function oftemperature regulating block 8 shown in FIG. 3. Temperature regulator 20constantly applies heat to temperature regulating block 8, whereastemperature regulator 9 cools the temperature regulating block, i.e.removes heat from it. Accordingly, a heat flux is set up throughtemperature regulating block 8 between temperature regulators 20 and 19.

The temperature function of FIG. 3a shows the temperature T over thepath S in which the temperature function is linear in the middle zone ofthe temperature regulating block 8. Near the left end, that is abovetemperature regulator 19, the temperature function becomes shallowerbecause the heating effectiveness of temperature regulator 20 decreasesever more toward the left end of temperature regulating block 8.

At the right side, that is above temperature regulator 20, thetemperature is linear to the end of the temperature regulating block asshown by FIG. 3a. This result is assured by two grooves 37 and 38extending parallel to the boundary between the areas of contacting side15 contacted by temperature regulators 19 and 20. These grooves reducethe cross-section of the temperature regulating block 8 and assure alocal increase in thermal impedance to the heat flux present in theblock between the heating and cooling temperature regulators 20 and 19resp., the block otherwise being of high thermal conductivity and, forinstance, made of metal. Because the slope of the temperature gradientof the temperature curve shown in FIG. 3a is proportional to the productof heat flux and thermal impedance, the shape of the temperature curvecan be controlled by locally changing the thermal impedance, and inparticular, as shown by FIG. 3a, the curve may be made straight. Forthis purpose, grooves 37 and 38 are of different depths, that is, theyreduce the block's cross-section differently. The depth andconfiguration of grooves 37 and 38 of FIG. 3 is merely illustrative. Theexact depth, position and number of grooves illustratively can bedetermined empirically.

FIG. 3a shows that the temperature slope becomes shallower at the leftside of temperature regulating block 8. This flattening is compensatedon the right side, that is by means of the temperature regulator 20, bythe presence of grooves 37 and 38. As shown by FIG. 3, groove 38 isdeeper than the groove 37 because it is nearer the right rim of theblock, that is, in a zone wherein the heat flux from temperatureregulator 20 to temperature regulator 19 is less than at the site ofgroove 37. To implement the same temperature gradient at groove 38,higher thermal impedance, namely a deeper groove, is required. If groove38 is deepened further, as indicated by broken lines 38′, thetemperature profile can be raised further in this zone as indicated bydash-dot lines in FIG. 3a.

FIG. 4 is a view similar to FIG. 3 of a temperature regulating block 48comprising three temperature regulators 19′, 19 and 20. If temperatureregulator 20 is heating and temperature regulator 19 is cooling, thetemperature is as shown by the curve in FIG. 4a. At the ends of thecurve, that is above temperature regulators 19′ and 20, the slope isshallower for lack of grooves above the temperature regulators such asthe grooves 37 and 38 of FIG. 3.

A linear temperature gradient is implemented by means of middletemperature regulator 19. Middle temperature regulator 19 can beoperated at an intermediate temperature or, where called for, it may beshut off. It is needed to prevent any temperature-curve deviation at themiddle of the block and in particular also when the temperature curve asa whole must be rapidly shifted to another level. It is also needed inthe alternative of the total block being set to the same temperature.

The temperatures must be regulated to achieve the required exacttemperature in temperature regulating block 48. For that purpose,temperature regulators 19′, 19 and 20 are each controlled in its owncontrol loop by sensors (not shown) mounted in block 48 above theindividual temperature regulators. Heat exchange takes place between thecontrol loops by heat flux in the block between the temperatureregulators. As a result, the control loops interact and controlfluctuations may arise which can be checked only with difficulty.

The fluctuations in regulation can be reduced by reducing the heat fluxbetween the temperature regulators. In the embodiment of FIG. 4, grooves39 increasing the thermal impedance between the temperature regulatorsare provided for such a purpose at the boundaries between the areas ofcontacting side 15 that are fitted with the temperature regulators 19′,19 and 20.

As further shown by FIG. 4, grooves 39 also may be machined from above,that is into the receiving side, as indicated in dashed lines by thegroove 39′. The grooves 37 and 38 of FIG. 3 alternatively also may befitted into the block from above, that is into the receiving side 10.

Grooves 37, 38 and 39 are shown in FIGS. 3 and 4 that are designed tohamper the heat flux in the temperature regulating block for a varietyof purposes, by reducing block cross-section, i.e. increasing itsthermal impedance. However, other zone-designs also may be used insteadof the shown grooves in the temperature regulating block, offering adifferent thermal conductivity or thermal impedance from the othersegments of the block. The grooves may be replaced, for instance, byzones in the temperature regulating block comprising a thermalconductivity, or impedance, different from other block regions.Illustratively, such zones may be created by splitting the block at thislocation and by sandwiching an insert of a material of higher thermalimpedance into the block. These zones, just as the grooves shown inFIGS. 3 and 4, can pass through in arbitrary linear manner, preferably,however, transversely to the heat flux and in a straight line betweentwo edges of the block. Illustratively, the grooves shown in FIGS. 3 and4 preferably run transversely to block 8 or 48, that is perpendicular tothe plane of the paper and through the entire block.

Each temperature regulating block 8 and 48 shown in FIGS. 3 and 4 isfitted with two temperature regulators 19, 20 or three temperatureregulators 19, 19′ and 20, which in each case cover the full width ofthe block. As shown by the temperature functions of FIGS. 3a and 4 a, atemperature gradient in this block therefore can be set up only in thelongitudinal direction, that is from left to right in the drawing.

FIG. 5 shows a variation of a temperature regulating block 58 in whichthe contacting side 15 is fitted with segment boundaries 61 and 62 andwith temperature regulators 59, 60, 59′ and 60′ in four quadrants. Iftemperature regulators 59 and 59′ are operated in an identical manner,for instance in the cooling mode, and if the temperature regulators 60and 60′ are operated at the same temperature, a temperature gradient inthe direction of the x-axis is set up in temperature regulating block58. If temperature regulators 59 and 60 and also temperature regulators59′ and 60′ are operated at the same temperature, then a temperaturegradient is set up in the perpendicular direction, i.e. in the y-axisdirection. If all temperature regulators are operated at the sametemperature, a constant temperature will be implemented over the entiretemperature regulating block 58.

The ability to generate a temperature gradient alternatingly in the x-or y-direction makes possible an operational variation wherein thetemperature regulating block 58 is operated successively at twodifferent temperature levels, for instance one at 30° C. and one at 60°C. At each level, the precisely optimal temperature is determined: thisgoal may be implemented in one pass, first the temperature regulatingblock being operated at the 30° C. level in the x-direction at agradient, this gradient for instance generating temperatures at thetemperature regulating block of 28, 29, 30, 31, 32° C. Thereupon thetemperature regulating block is set at the 60° C. temperature with atemperature gradient in the y-direction, different temperatures forinstance of 58, 59, 60, 61, 62° C. being produced in the y-direction. Ifin the process the temperature regulating block holds samples to betemperature-regulated and arrayed over its surface in regular rows (xdirection) and columns (y direction), then such samples can next beanalyzed and those that were optimally temperature regulated can bedetermined. As regards the latter, they had been subjected to theoptimal temperature at each temperature level.

A further operational variation is significant, namely one wherein allfour temperature regulators are kept at different temperatures. In sucha case a complex temperature function can be applied with temperaturesdiffering both in the x and in the y directions. Illustratively, alarger temperature gradient can be set, for instance, in the x directionand a smaller one in the y direction. If seats are provided at thereceiving side of temperature regulating block 58 to accept receptaclesin rows (x direction) and columns (y direction), then illustrativelytemperature differences of 1° C. may be set between the rows andtemperature differences of 0.1° C. between the columns. As a result,temperature differentials of 10° C. with a resolution of 0.1° C. canthus be set.

FIGS. 6 and 7 are resp. a top view of the receiving side and across-section of a temperature regulating block 68 of which theconfiguration substantially corresponds to that of the already discussedtemperature regulating block 8, that is, being in contact at its contactside 15 with two temperature regulators 19 and 20.

Two different kinds of seats 71 and 72 in the form of recesses ofdifferent depths are formed in the receiving side.

As shown in FIG. 6, the two kinds of seats 71 and 72 nest among eachother in a rectangular grid pattern in such a way that a seat 72 of thesecond kind is each time located between four seats 71 of the firstkind, and vice-versa. As shown in FIG. 7, the block thereby assume afiligree construction of much reduced cross-section in the upper portionof the block, that is toward its receiving side. In addition, oval holes73 are inserted between seats 71 and 72, each being located centrallybetween two larger seats 71 and two smaller seats 72, as shown in FIG.6. Temperature regulating block 70 as a result is additionally thinnedin its upper portion. Therefore, the heat conduction between thetemperature regulators 20 and 19 is less in its upper portion thinned bythe seats 71, 72 and the holes 73 than in the zone of the lower,continuous plate 74 running continuously underneath all seats 71, 72 andholes 73.

As shown in FIG. 6, in this embodiment, the volume of temperatureregulating block 68 is substantially reduced, in particular at its thickupper zone away from the contacting side 15. As a result, the heatcapacity of the temperature regulating block is much reduced. It followsthat the temperature regulating block can be made to assume very rapidlya desired temperature, for instance cooling it or heating it to anothertemperature level. Accordingly, in the lab thermostatting system shownin FIG. 1 or 2, one of the shown temperature regulating blocks can beoperated consecutively at different temperature levels. In particular,neighboring temperature levels may be implemented in one temperatureregulating block whereas another temperature regulating block is usedfor a more remote temperature level. As regards the conventional threetemperature levels for PCR, illustratively two temperature levels may beimplemented in one block and another in a second block. The large areaof contact between the temperature regulating block and the temperatureregulators shown in the Figures helps much to achieve quick heating orcooling.

The design for low mass of the temperature regulating block 68 shown inFIGS. 6 and 7 assures not only much reduced heat capacity of thetemperature regulating block but also offers reduced thermalconductivity, i.e. high thermal impedance of the temperature regulatingblock in the direction of heat flux between the temperature regulators20 and 19. To implement a desired temperature profile, i.e. temperaturegradient as illustratively shown in FIGS. 3a and 4 a, only a low heatflux is needed because of the high thermal impedance. Therefore thetemperature regulators 19 and 20 need only offer low power.

Temperature regulating block 68 shown in FIGS. 6 and 7 comprises agroove 69 used to thermally decouple the temperature regulators 20 and19 from each other as explained in relation to FIG. 4. As sectionallyshown in FIG. 7, groove 69 is stepped in order to penetrate as deeply aspossible between the seats 71, 72 and holes 73 without, however,touching them. As shown in dashed lines in FIG. 6, groove 69 accordinglymeanders between the recesses and holes. Illustratively, the showntemperature regulating block 68, for instance of aluminum, may bemold-cast or be manufactured with a numerically controlled millingmachine.

In a manner to groove 39 shown in dashed lines in FIG. 4, groove 69 ofFIGS. 6 and 7 can be machined on the receiving side, that is from aboveinto the temperature regulating block 68. Illustratively, this groove 69may run transversely through recesses 71, 72 and holes 73, or it maymeander around them, for instance in the form of a very narrow and deepslit.

What is claimed is:
 1. A temperature regulating block for a laboratorythermostating system, comprising: a body having a receiving side; aplurality of first recesses for receiving first receptacles anddimensioned to provide a large-area contact between each of the firstrecesses and a respective first receptacle, whereby a heat transferrelationship between the body and the first receptacles is provided; aplurality of second recesses for receiving second receptacles anddimensioned to provide a large-area contact between each of the secondrecesses and a respective second receptacle, whereby a heat transferrelationship between the body and the second receptacles is provided;and at least one temperature regulator in contact with the body, whereinthe first recesses and the second recesses are arranged in a regular,two-dimensional grid such that each of the first recesses is locatedbetween four second recesses, and each of the second recesses is locatedbetween four first recesses, wherein the receiving side has a pluralityof holes, with each hole being located between two first recesses andtwo second recesses, and wherein the at least one temperature regulatorcomprises a continuous plate arranged underneath the first and secondrecesses and the holes.
 2. A temperature regulating block according toclaim 1, wherein the body comprises a groove forming a zone of thermalimpedance higher than thermal impedance of a remainder of the body.
 3. Atemperature regulating block according to claim 2, wherein the body hasa contacting side opposite the receiving side, and the groove is formedin the contacting side.
 4. A temperature regulating block according toclaim 3, wherein the groove has a depth larger than a thickness of thecontinuous plate and meanders between the first and second recesses andthe holes.
 5. A temperature regulating block for a laboratorythermostating system, comprising: a body having a receiving side; aplurality of first recesses for receiving first receptacles anddimensioned to provide a large-area contact between each of the firstrecesses and a respective first receptacle, whereby a heat transferrelationship between the body and the first receptacles is provided; aplurality of second recesses for receiving second receptacles anddimensioned to provide a large-area contact between each of the secondrecesses and a respective second receptacle, whereby a heat transferrelationship between the body and the second receptacles is provided;and at least one temperature regulator in contact with the body, whereinthe first recesses and the second recesses are arranged in a regular,two-dimensional grid such that each of the first recesses is locatedbetween four second recesses, and each of the second recesses is locatedbetween four first recesses, wherein the body has a contacting sideopposite the receiving side, and wherein the temperature regulatingblock comprises a plurality of temperature regulators arranged at thecontacting side and forming a large-area contact with respectivesegments of the contacting side, the plurality of temperature regulatorsregulating the respective segments at different temperatures.
 6. Atemperature regulating block for a laboratory thermostating system,comprising: a body having a receiving side; a plurality of firstrecesses formed in the receiving side for receiving first receptaclesand having a first diameter; a plurality of second recesses formed inthe receiving side for receiving second diameter different from thefirst diameter; and at least one temperature regulator in contact withthe body, wherein the plurality of first recesses and the plurality ofsecond recesses are arranged in respective plane rectangular gridsarranged parallel to each other and offset relative to each in oppositedirections of the grid by ½ grid constant; and wherein the grid constantand the first and second diameters are so selected that each of thefirst recesses and each of the second recesses are separated,respectively, from four second recesses and four first recesses bynarrow webs.